# encoding: utf-8

import logging
import sys
import cgitb
import warnings
import xml.dom.minidom
import urllib2

from paste.deploy.converters import asbool

import ckan.model as model
import ckan.plugins as p
import ckan.logic as logic

from common import (SearchIndexError, SearchError, SearchQueryError,
                    make_connection, is_available, SolrSettings)
from index import PackageSearchIndex, NoopSearchIndex
from query import (TagSearchQuery, ResourceSearchQuery, PackageSearchQuery,
                   QueryOptions, convert_legacy_parameters_to_solr)

log = logging.getLogger(__name__)


def text_traceback():
    with warnings.catch_warnings():
        warnings.simplefilter("ignore")
        res = 'the original traceback:'.join(
            cgitb.text(sys.exc_info()).split('the original traceback:')[1:]
        ).strip()
    return res


SUPPORTED_SCHEMA_VERSIONS = ['2.8', '2.9']

DEFAULT_OPTIONS = {
    'limit': 20,
    'offset': 0,
    # about presenting the results
    'order_by': 'rank',
    'return_objects': False,
    'ref_entity_with_attr': 'name',
    'all_fields': False,
    'search_tags': True,
    'callback': None,  # simply passed through
}

_INDICES = {
    'package': PackageSearchIndex
}

_QUERIES = {
    'tag': TagSearchQuery,
    'resource': ResourceSearchQuery,
    'package': PackageSearchQuery
}

SOLR_SCHEMA_FILE_OFFSET_MANAGED = '/schema?wt=schema.xml'
SOLR_SCHEMA_FILE_OFFSET_CLASSIC = '/admin/file/?file=schema.xml'


def _normalize_type(_type):
    if isinstance(_type, model.domain_object.DomainObject):
        _type = _type.__class__
    if isinstance(_type, type):
        _type = _type.__name__
    return _type.strip().lower()


def index_for(_type):
    """ Get a SearchIndex instance sub-class suitable for
        the specified type. """
    try:
        _type_n = _normalize_type(_type)
        return _INDICES[_type_n]()
    except KeyError as ke:
        log.warn("Unknown search type: %s" % _type)
        return NoopSearchIndex()


def query_for(_type):
    """ Get a SearchQuery instance sub-class suitable for the specified
        type. """
    try:
        _type_n = _normalize_type(_type)
        return _QUERIES[_type_n]()
    except KeyError as ke:
        raise SearchError("Unknown search type: %s" % _type)


def dispatch_by_operation(entity_type, entity, operation):
    """Call the appropriate index method for a given notification."""
    try:
        index = index_for(entity_type)
        if operation == model.domain_object.DomainObjectOperation.new:
            index.insert_dict(entity)
        elif operation == model.domain_object.DomainObjectOperation.changed:
            index.update_dict(entity)
        elif operation == model.domain_object.DomainObjectOperation.deleted:
            index.remove_dict(entity)
        else:
            log.warn("Unknown operation: %s" % operation)
    except Exception as ex:
        log.exception(ex)
        # we really need to know about any exceptions, so reraise
        # (see #1172)
        raise


class SynchronousSearchPlugin(p.SingletonPlugin):
    """Update the search index automatically."""
    p.implements(p.IDomainObjectModification, inherit=True)

    def notify(self, entity, operation):
        if not isinstance(entity, model.Package):
            return
        if operation != model.domain_object.DomainObjectOperation.deleted:
            dispatch_by_operation(
                entity.__class__.__name__,
                logic.get_action('package_show')(
                    {'model': model, 'ignore_auth': True, 'validate': False,
                     'use_cache': False},
                    {'id': entity.id}),
                operation
            )
        elif operation == model.domain_object.DomainObjectOperation.deleted:
            dispatch_by_operation(entity.__class__.__name__,
                                  {'id': entity.id}, operation)
        else:
            log.warn("Discarded Sync. indexing for: %s" % entity)


def rebuild(package_id=None, only_missing=False, force=False, refresh=False,
            defer_commit=False, package_ids=None, quiet=False):
    '''
        Rebuilds the search index.

        If a dataset id is provided, only this dataset will be reindexed.
        When reindexing all datasets, if only_missing is True, only the
        datasets not already indexed will be processed. If force equals
        True, if an exception is found, the exception will be logged, but
        the process will carry on.
    '''
    log.info("Rebuilding search index...")

    package_index = index_for(model.Package)
    context = {'model': model, 'ignore_auth': True, 'validate': False,
        'use_cache': False}

    if package_id:
        pkg_dict = logic.get_action('package_show')(context,
            {'id': package_id})
        log.info('Indexing just package %r...', pkg_dict['name'])
        package_index.remove_dict(pkg_dict)
        package_index.insert_dict(pkg_dict)
    elif package_ids:
        for package_id in package_ids:
            pkg_dict = logic.get_action('package_show')(context,
                {'id': package_id})
            log.info('Indexing just package %r...', pkg_dict['name'])
            package_index.update_dict(pkg_dict, True)
    else:
        package_ids = [r[0] for r in model.Session.query(model.Package.id).
                       filter(model.Package.state != 'deleted').all()]
        if only_missing:
            log.info('Indexing only missing packages...')
            package_query = query_for(model.Package)
            indexed_pkg_ids = set(package_query.get_all_entity_ids(
                max_results=len(package_ids)))
            # Packages not indexed
            package_ids = set(package_ids) - indexed_pkg_ids

            if len(package_ids) == 0:
                log.info('All datasets are already indexed')
                return
        else:
            log.info('Rebuilding the whole index...')
            # When refreshing, the index is not previously cleared
            if not refresh:
                package_index.clear()

        total_packages = len(package_ids)
        for counter, pkg_id in enumerate(package_ids):
            if not quiet:
                sys.stdout.write(
                    "\rIndexing dataset {0}/{1}".format(
                        counter +1, total_packages)
                )
                sys.stdout.flush()
            try:
                package_index.update_dict(
                    logic.get_action('package_show')(context,
                        {'id': pkg_id}
                    ),
                    defer_commit
                )
            except Exception as e:
                log.error(u'Error while indexing dataset %s: %s' %
                          (pkg_id, repr(e)))
                if force:
                    log.error(text_traceback())
                    continue
                else:
                    raise

    model.Session.commit()
    log.info('Finished rebuilding search index.')


def commit():
    package_index = index_for(model.Package)
    package_index.commit()
    log.info('Commited pending changes on the search index')


def check():
    package_query = query_for(model.Package)

    log.debug("Checking packages search index...")
    pkgs_q = model.Session.query(model.Package).filter_by(
        state=model.State.ACTIVE)
    pkgs = set([pkg.id for pkg in pkgs_q])
    indexed_pkgs = set(package_query.get_all_entity_ids(max_results=len(pkgs)))
    pkgs_not_indexed = pkgs - indexed_pkgs
    print('Packages not indexed = %i out of %i' % (len(pkgs_not_indexed),
                                                   len(pkgs)))
    for pkg_id in pkgs_not_indexed:
        pkg = model.Session.query(model.Package).get(pkg_id)
        print(pkg.revision.timestamp.strftime('%Y-%m-%d'), pkg.name)


def show(package_reference):
    package_query = query_for(model.Package)

    return package_query.get_index(package_reference)


def clear(package_reference):
    package_index = index_for(model.Package)
    log.debug("Clearing search index for dataset %s..." %
              package_reference)
    package_index.delete_package({'id': package_reference})


def clear_all():
    package_index = index_for(model.Package)
    log.debug("Clearing search index...")
    package_index.clear()

def _get_schema_from_solr(file_offset):
    solr_url, solr_user, solr_password = SolrSettings.get()

    http_auth = None
    if solr_user is not None and solr_password is not None:
        http_auth = solr_user + ':' + solr_password
        http_auth = 'Basic ' + http_auth.encode('base64').strip()

    url = solr_url.strip('/') + file_offset

    req = urllib2.Request(url=url)
    if http_auth:
        req.add_header('Authorization', http_auth)

    return urllib2.urlopen(req)

def check_solr_schema_version(schema_file=None):
    '''
        Checks if the schema version of the SOLR server is compatible
        with this CKAN version.

        The schema will be retrieved from the SOLR server, using the
        offset defined in SOLR_SCHEMA_FILE_OFFSET_MANAGED
        ('/schema?wt=schema.xml'). If SOLR is set to use the manually
        edited `schema.xml`, the schema will be retrieved from the SOLR
        server using the offset defined in
        SOLR_SCHEMA_FILE_OFFSET_CLASSIC ('/admin/file/?file=schema.xml').

        The schema_file parameter allows to override this pointing to
        different schema file, but it should only be used for testing
        purposes.

        If the CKAN instance is configured to not use SOLR or the SOLR
        server is not available, the function will return False, as the
        version check does not apply. If the SOLR server is available,
        a SearchError exception will be thrown if the version could not
        be extracted or it is not included in the supported versions list.

        :schema_file: Absolute path to an alternative schema file. Should
                      be only used for testing purposes (Default is None)
    '''

    if not is_available():
        # Something is wrong with the SOLR server
        log.warn('Problems were found while connecting to the SOLR server')
        return False

    # Try to get the schema XML file to extract the version
    if not schema_file:
        try:
            # Try Managed Schema
            res = _get_schema_from_solr(SOLR_SCHEMA_FILE_OFFSET_MANAGED)
        except urllib2.HTTPError:
            # Fallback to Manually Edited schema.xml
            res = _get_schema_from_solr(SOLR_SCHEMA_FILE_OFFSET_CLASSIC)
    else:
        url = 'file://%s' % schema_file
        res = urllib2.urlopen(url)

    tree = xml.dom.minidom.parseString(res.read())

    version = tree.documentElement.getAttribute('version')
    if not len(version):
        raise SearchError('Could not extract version info from the SOLR'
                          ' schema, using file: \n%s' % url)

    if not version in SUPPORTED_SCHEMA_VERSIONS:
        raise SearchError('SOLR schema version not supported: %s. Supported'
                          ' versions are [%s]'
                          % (version, ', '.join(SUPPORTED_SCHEMA_VERSIONS)))
    return True
